1. Technical Field
The present invention relates to an input device and an electronic information board system employing the input device.
2. Background Art
The development of electronic information boards such as electronic blackboards and interactive whiteboards (IWB) has been progressing. The electronic information board includes, for example, an image display apparatus, a coordinate detector and a control apparatus. The image display apparatus employs a relatively large screen using a flat panel such as a liquid crystal panel and a plasma panel having a diagonal size of 40 to 60 inches. The coordinate detector (e.g., touch panel) detects coordinates of positions where a pen-like input device contacts on a display face of the image display apparatus. The control apparatus displays various images such as characters, numbers and figures based on coordinates data output from the coordinate detector, written on the display face of the image display apparatus using the pen-like input device.
Further, by connecting the electronic information board to a personal computer (PC), an image displayed on a display of the PC can be enlarged and displayed on the electronic information board, which may be used for presentation on meetings.
When the input operation of the pen-like input device is conducted to the electronic information board, operation-in-progress signals indicating the input operation is being conducted should be sent to the electronic information board. If a finger or a hand of an operator or other person touches the touch panel of the electronic information board, unintentional writing and erasing may occur. Further, if the pen-like input device has a plurality of functions such as writing and erasing (eraser), signal should be sent to the electronic information board which function is conducted.
Conventionally, the pen-like input device has a writing unit, and a pen end made of an elastic member such as rubber. When the pen end is moved on the touch panel while being contacted, the writing unit detects a writing operation and outputs a writing-operation-in-progress signal to the electronic information board such as a touch panel. The movement of the pen end on the display face while being contacted on the display face of the electronic information board can be detected by an optical sensor such as the touch panel as coordinates of contacting positions, with which characters and figures can be written similar to usual handwritten blackboards and whiteboards.
If the writing-operation-in-progress signal is not detected, the electronic information board does not receive an input, which means that the electronic information board displays characters and figures written on the display face based on contacting position information of the pen-like input device contacting the display face and an operation signal (writing-operation-in-progress signal) output from the pen-like input device. Therefore, to conduct writing to the electronic information board, the pen-like input device needs to transmit a signal that the pen end is contacted (pressed) to the display face to the electronic information board by wireless communication using infrared ray or the like. Further, because the pen-like input device is operated while being held by a hand, a wireless signal using infrared ray needs to be output all round directions of the pen-like input device.
Conventionally, a pen input device 400 having a light emitting unit shown in FIG. 11 is used. FIG. 11A is a schematic cross-sectional view of the pen input device 400, and FIG. 11B is a cross-sectional view of FIG. 11 A cut at A-A line or B-B line. The pen input device 400 conducts wireless communication such as infrared ray communication to transmit a writing-operation-in-progress signal indicating that the pen input device 400 is touching a touch panel, and an erasing-operation-in-progress signal indicating that the pen input device 400 is conducting an erasing. The pen input device 400 needs to radiate infrared ray to 360 degrees about the pen axis to secure wireless communication (e.g., infrared ray communication) with the electronic information board for operations under any kind of situations.
Further, the pen input device 400 has a two ends such as a front end and a rear end. When writing and erasing operations are conducted, a user holds the pen input device 400 upside-down. Therefore, a light emitting unit (i.e., light source) for infrared ray communication needs to be disposed at the front end and the rear end. Therefore, as shown in FIG. 11, a light emitting diode (LED) is disposed at each of a top face, a back face, and two side faces of a board disposed in a body for both of the front end, the rear end, which means eight LEDs 401 are installed to conduct infrared ray radiation 402 to all directions. Therefore, greater power consumption is required for emitting light from the LEDs 401, with which battery life of the pen input device 400 becomes significantly short.